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Event Log : Unicast Maintenance Ranging - 6750 ranging
Introduction ' ' ''' '''What is an event log Event logs are designed as an information scheme for tech's companies regarding customer’s connection and diagnosis among the CMTS(cable modem termination system, sited in the cable company's headend or hubsite) and the CPE(customer-provided equipment)'. ' ' '''Features of cable gateway / what they are used for ' Implemented on the CPE these messages can be found on your modem under Maintenance event logs. We definitely need to elaborate on what these messages mean, and in order to troubleshoot the issue we will need to keep track of the logs. Messages as “Unicast Maintenance Ranging” may seem strange when the modem is unable to reach the equipment at service provider, and it is not able to finish the standard periodic keep alive that cable modems do. '''Understanding Event Logs In order to understand Unicast Maintenance Ranging lets see a schema of the CPE connecting to the CMTS and the message timeouts. 1. T1 (No UDC Received) '''The modem will search for a digital QAM channel (digital cable channel encoding) and waits for upstream channel descriptor (UCD). If UCD not received in a due time, a T1 timeout follows and the modem will search for another digital QAM channel. 2. '''T2 (No Maintenance Broadcast for Ranging opportunities received) '''When the modem discovers the right downstream channel and gets the upstream channel descriptor, will wait for its primary opportunity to "communicate" to the CMTS. If that doesn’t happen then within a few seconds, a T2 timeout occurs. 3. '''T3 (Ranging Request retries Exhausted) Detecting a downstream data carrier channel, the modem finds the opportunity to "exchange data" (DHCP, TFTP, TOD processes will follow) with the CMTS which takes several data exchanges. If the modem doesn't get an answer from the CMTS within about 200 milliseconds, a T3 timeout follows. The modem will reset its cable interface and restart the registration process. 4. T4 (No Unicast opportunities received) '''After the modem is connected, the CMTS propagates "Periodic Ranging" or keep-alive requests to it every ½ min. and in the case that the modem doesn't get one, a T4 timeout occurs. Once 16 of the T4 timeouts have to follow, the modem resets. '''Reasons of Unicast Maintenance Event logs If there is a downstream exchange difficulty, "keep-alive requests" will not be received by the modem. * Numerous modems connected to the same upstream port * Coaxial connection is loose * Signal of the cable is not strong. * Outages in the CPE area. * Replaced or upgrade modem to match the bandwidth speeds * Performance can be affected by the heavy upstream usage of programs such as Skype, peer to peer file sharing (uTorrent). Overloading and causing it to reset internally, giving the effect of a disconnection. * The use of PPPoE or PPPoA (depending on what do we use to contact the ISP) Conclusion ''' Event logs helps us understand and troubleshoot connectivity between the two far ends and depending on the messages from the event log we can resolve in-between issues. '''Refence Links Started Unicast Maintenance Ranging - No Response received Modems: What do messages about timeouts mean? DSL Modem Router guide Connectivity Modem drops connecting whenever uploading Unicast Maintenance Ranging Netgear CG3100D-2 Event Log Issues